2-Pivaloylamino-6-formylpterin (1a) and a series of other important heterocyclic aldehydes (2a, 3a, 4a, 6a, and 7a) have been synthesized in good yield by microwave assisted selenium dioxide oxidation. Interestingly, 2-methylpyrazine gives 2-pyrazinecarboxylic acid (5a) under the similar condition.